Hi everyone,
I am relatively new to Arduino and electronics in general so I often visit the forum in search of answers and advice. This time I came across a problem for which I couldn't find the answer so I am hoping someone will be able to give some insight.
I am building a project where I am using a cheap Chinese 16x2 LCD with integrated I2C shield along with an RTC module which is also connected over I2C pins to Arduino Nano. I plan for the circuit to be turned on pretty much 24/7 while the display is needed only for a short time while changing the settings. That's why I decided to use a logic level MOSFET to completely turn off the display while it's not needed, and it worked great. The problem appeared when I connected an RTC module which uses the same I2C pins. Every time Arduino reads from the RTC, LCD backlight, and power led on the back of the LCD module blink briefly even though the module is supposed to be completely off. Except for that, both modules work as expected and there are no other problems.
If I disconnect the LCD's positive lead the blinking stops, but when I disconnect the negative lead connected to the MOSFET the blinking continues, suggesting it's not MOSFET's fault.
I assume the I2C signal somehow allows the LCD to be powered but I don't know if it is because of the faulty LCD module, or that behavior is expected.
I don't like the idea of LCD being turned on every second or so, and it kind of beats the purpose of implementing the MOSFET to keep it off.
Sorry for the long post
Thank you